Electric motor

Abstract

The present application discloses an electric motor. The electric motor comprises a brush holder arranged between a magnetic pole housing and a drive element. A rotor passes through the brush holder to connect to the drive element. A mounting slot is provided on the brush holder. The mounting slot has a wall that defines an interior space. At its end, the mounting slot has an opening. A thermal shield is mounted through this opening in the interior space. An elastic arm is arranged on the wall. The elastic arm is elastically deformed to rest against a side surface of the thermal shield. The elastic action of the arm allows the mounting slot to accommodate thermal shields of varying thicknesses.

Description

Technical field

[0001] The present application relates to a small electric motor, specifically to an electric motor used to drive moving components. State of the art

[0002] Vehicles contain numerous moving components such as seats, steering wheel, panoramic sunroof, side windows, steering column, etc. These components are moved by electric motors. Electric motors comprise a stator-rotor assembly as the power source and a drive section as the output. An electric motor can refer to a brushed motor. A brushed motor includes a brush holder for the brushes. In addition to arranging the brushes, a brush holder has other functions, such as enclosing magnetic pole housings, supporting electronic components, forming a wiring connection section, or mounting the magnetic pole housing to the drive section housing, etc. As technology has advanced, state-of-the-art brush holders face challenges in many aspects, such as integration density, compatibility, circuit protection, assembly process, manufacturing costs, etc. Disclosure of the invention

[0003] One aspect of the present application is to provide an electric motor that has a brush carrier with improved functionality.

[0004] The electric motor comprises a brush carrier arranged between a magnetic pole housing and a drive unit; a rotor passes through the brush carrier to connect with the drive unit; a mounting slot is arranged on the brush carrier; the mounting slot has a wall that defines an interior space; at the head end, the mounting slot has an opening; a thermal guard is mounted through the opening in the interior space; an elastic arm is arranged on the wall; the elastic arm is elastically deformed to rest against a side surface of the thermal guard.

[0005] In one embodiment of the electric motor, the elastic arm comprises an elongated plate, the plate has a height in the vertical direction of the wall, the height of the plate being more than 1 / 4 of the height of the wall.

[0006] In one embodiment of the electric motor, the brush holder is manufactured from plastic using injection molding.

[0007] In one embodiment of the electric motor, the mounting slot is designed such that the position of the thermal protection in the mounting slot is limited at the location of the opening by means of the lower part of the mounting slot, elastic arm and the connecting pins of the thermal protection.

[0008] In one embodiment of the electric motor, an extension section extends along the wall at the lower part of the mounting slot, the wall has a first base support, the extension section has a cavity that is smaller than the interior, and a second base support that is deeper than the first base support, wherein the second base support is designed to support the first thermal protection, and the first base support is designed to support a second thermal protection that has different dimensions than the first thermal protection.

[0009] In one embodiment of the electric motor, the elastic arm is located on a side wall in the mounting slot, and the elastic arm includes a support section that projects from an end section of the plate towards the interior, the support section having a surface that rests against a side surface of the thermal shield.

[0010] In one embodiment of the electric motor, a heat conduction bore is arranged on the side wall opposite this side wall.

[0011] In one embodiment of the electric motor, a different heat conduction bore is arranged on the second base support.

[0012] In one embodiment of the electric motor, the mounting slot is integrated into the brush holder, and the brush holder comprises a carrier plate, wherein the carrier plate has a first side and an opposite second side on which carbon brushes are arranged, and the circuit board is arranged on the second side.

[0013] In one embodiment of the electric motor, the elastic arm of the mounting slot is shaped so that it protrudes from the first side.

[0014] In one embodiment of the electric motor, the extension section is shaped so that it protrudes from the second side and has a first partition wall extending towards the outside of the mounting slot, the first partition wall being located between the circuit board and the bearing bore of the brush carrier, the rotor being supported by the cooperation of the bearing bore.

[0015] In one embodiment of the electric motor, the second partition is shaped so that it protrudes from the first side to cover the process bore that passes through the first and second sides of the carrier plate.

[0016] In one embodiment of the electric motor, several pins are arranged on the second side to position the circuit board, and one pin is designed to have a guide section for passing through the circuit board, a positioning platform as a stop to terminate the passage through the circuit board, and an interaction section between the guide section and the positioning platform, wherein the interaction section interacts with the position hole of the circuit board.

[0017] In one embodiment of the electric motor, the interaction section is designed as several parts that extend the cylindrical body of the pin to provide a filling between the positioning hole and the pin, each of these parts having an arc-shaped outer surface that follows the corresponding contour of the positioning hole.

[0018] In one embodiment of the electric motor, the circuit board is designed to have a heteromorphic contour.

[0019] In one embodiment of the electric motor, the circumference of the bearing bore has a passage where a portion has been cut off to interact with the contour of a part of the circuit board, the contour of other parts of the circuit board following the shape of the brush carrier.

[0020] In one embodiment of the electric motor, the brush carrier integrates a terminal socket on its radial outer edge, with several terminals with pins being inserted under pressure into a slot of the terminal socket to establish a connection between the terminal socket and the circuit board mounted on the brush carrier.

[0021] The arm, positioned against one wall of the mounting slot, can provide lateral pressure for the thermal break insert into the slot. When a side surface of the thermal break rests against the elastic arm, the arm also provides a certain frictional resistance that prevents the thermal break from detaching from the mounting slot. The elastic action of the arm allows the mounting slot to accommodate thermal break inserts of varying thicknesses.With relatively thin thermal shields, the deformation of the elastic arm is comparatively small, but with relatively thick thermal shields, the deformation of the elastic arm is comparatively large. Therefore, mounting slots according to the present application can accommodate both conventional, commercially available thermal shields and novel thermal shields. Conventional and novel thermal shields exhibit structural differences, resulting in different dimensions and sizes. Furthermore, the present application is not only suitable for thermal shields of varying thicknesses, but its structural design also provides mounting cavities and stops in multiple directions to stabilize the thermal shields within the mounting slot.

[0022] By arranging partitions on the brush carrier, an electric motor according to the present application can prevent carbon dust originating from the carbon brushes from contaminating the various components of the brush carrier; this applies in particular to conductor tracks and all types of electronic components. The presence of partitions can prevent carbon dust from adhering to these components, thus protecting their efficiency.

[0023] The pins of the brush carrier according to the present application not only serve to provide a guide for the printed circuit board during assembly, but can also prevent the printed circuit board from falling off after assembly or when the printed circuit board is turned over.

[0024] Furthermore, the present application provides a printed circuit board (PCB) having a special shape, namely a "D" shape, which requires little space and occupies less than half the space on the brush holder, and in which all necessary electronic components for the brush holder are integrated. Furthermore, the present application provides a brush holder with a high degree of integration and a simple exterior.

[0025] With regard to the drive / drive aspect, the terminal pins are not only simplified in their structure through their design, but also offer a novel assembly method. Compared to the current method, in which terminals are integrated with the brush holder into a single unit by injection molding, the present application simplifies the manufacturing process by means of a method in which the terminals are mounted under pressure in the connection socket.

[0026] The present application provides an electric motor featuring a novel brush holder. This application can be implemented by modifying conventional brush holders. The novel brush holder, including the mounting slot, multiple partitions, and multiple pins, is injection-molded in one piece and offers advantages such as compatibility with various electronic components, protection of the printed circuit board, an optimized structure, and user-friendly assembly. As a result, an electric motor according to the present application exhibits remarkable features such as a high degree of adaptability, a high level of integration, and low manufacturing costs.

[0027] Further aspects and special features of the present application are clarified in the detailed description below, with reference to the accompanying drawings. It is understood, however, that the accompanying drawings serve only explanatory purposes and do not constitute a limitation of the scope of the present application, but merely refer to the accompanying claims. Furthermore, it is understood that the accompanying drawings are intended only to conceptually explain the described structures and processes. Unless otherwise stated, the figures are not necessarily drawn to scale. Description of the characters

[0028] Referencing the accompanying figures supports the specific description of concrete embodiments for a deeper understanding of the present application. In the figures, identical reference numerals consistently refer to identical elements in the figures. The following applies: Fig. Figure 1 is a schematic representation of an embodiment of an electric motor according to the present application; the Fig. 2 and Fig. Figure 3 shows schematic representations of a brush carrier of an electric motor according to the present application from different perspectives, showing Fig. 2. Remove the brush holder from the first side, Fig. 3. Remove the brush holder from the second side, Fig. Figure 4 is an interior view of a mounting slot of an electric motor according to the present application; Fig. Figure 5 is a partial view of the mounting slot made of Fig. 4 from the outside; Fig. 6 is a representation of a first thermal protection device that is mounted in the mounting slot; Fig. 7 is a representation of a second thermal protection device that is mounted in the mounting slot; Fig. Figure 8 is a schematic representation of a brush carrier of a further embodiment of an electric motor according to the present application; Fig. 9 is a schematic representation of a brush carrier or of another embodiment of an electric motor according to the present application; Fig. Figure 10 is a schematic representation of a pin serving as a guide for a printed circuit board, an embodiment of an electric motor according to the present application; Fig. 11 is a cross-sectional representation of how the pen is made of Fig. 10 interacts with the position hole of the circuit board; Fig. 12 is a schematic representation of a brush carrier of another embodiment of an electric motor according to the present application; Fig. 13 is a schematic representation of a terminal of an embodiment of an electric motor according to the present application; Fig. 14 is a schematic representation of another terminal of an embodiment of an electric motor according to the present application; Fig. Figure 15 is an internal representation of a terminal socket of an electric motor according to the present application, after a terminal has been mounted in the terminal socket; and Fig. 16 is an external representation of a clamp made of Fig. 15 after their installation in the connector socket from a different perspective. Specific embodiments

[0029] In order to assist technical experts in the relevant field in understanding the main subject matter of the claims of the present application precisely, specific embodiments of the present application are described in detail below in combination with the accompanying drawings.

[0030] Fig. Figure 1 is a schematic representation of an embodiment of an electric motor according to the present application. The electric motor comprises a magnetic pole housing 12, a brush holder 14, and a drive housing 16. The brush holder 14 is located at least partially in the central housing 13 between the magnetic pole housing 12 and the drive housing 16. The brush holder 14 is formed from plastic by injection molding. The rotor and the stator are arranged in the magnetic pole housing 12. The brush holder 14 abuts the magnetic pole housing 12 and can close the magnetic pole housing 12. The drive element (not shown) is arranged in the drive housing 16. Inside the electric motor, the rotor passes through the brush holder 14 to connect with the drive element. In one embodiment, the electric motor is a small electric motor, for example, a DC permanent magnet motor.

[0031] The Fig. 2 and Fig. Figure 3 shows schematic representations of the brush carrier of an embodiment of an electric motor according to the present application from different perspectives. The brush carrier 14 comprises a carrier plate 18, wherein the carrier plate 18 has a first side 20 and a second side 22, which are opposite each other. Fig. Figure 2 shows the arrangement of the first side. On the first side 20, a pair of brushes (not shown) is arranged diagonally by means of holders 17. Fig. Figure 3 shows the arrangement of the second side. A printed circuit board 24 is arranged on the second side 22. The brush carrier 14 further comprises a centrally arranged bearing bore 26, which serves for the passage of the rotor, the bearing bore 26 being simultaneously arranged on the second side 22. When the brush carrier 14 extends the magnetic pole housing made of Fig. Once 1 is closed, the first side 20 faces the interior of the magnetic pole housing.

[0032] How Fig. Figure 2 shows that the mounting slot 28 for the thermal protection device (not shown) is located near a pair of brushes. The thermal protection device is mounted on the first side 20 in the mounting slot 28. Pins of the mounted thermal protection device protrude from the mounting slot. The thermal protection device, also known as a temperature controller or thermal switch, is a safety device that prevents overheating in certain components of the electric motor. Conventional thermal protection devices consist of a housing and positive and negative pins on the housing. The housing is essentially rectangular.

[0033] Fig. Figure 4 shows the internal structure of the mounting slot. The mounting slot 28 has a wall 36 that defines an interior space 38. To accommodate the thermal insulation, the mounting slot 28 is designed to have a rectangular interior space 38. At its head end, the mounting slot 28 has an opening 40. The thermal insulation is mounted through the opening 40 in the mounting direction indicated by f in the figure, within the interior space 38 of the mounting slot 28. An elastic arm 50 is arranged on the wall 36 at the location of the opening 40. The structure of the elastic arm 50 ensures that a side surface of the thermal insulation mounted in the mounting slot 28 rests against the elastic arm 50. In one embodiment, the elastic arm 50 is slightly chamfered towards the interior space, so that, as shown in Figure 4, the thermal insulation is positioned within the interior space 38. Fig. Figure 4 shows the thermal break contacting the elastic arm 50 in the mounting slot 28. After contact, the elastic arm 50 deforms again in the opposite direction, and the elastic force generated by the deformation can cause the elastic arm 50 to exert lateral pressure on the thermal break. Regardless of the thickness of the thermal break, the elastic arm 50 can generate pressure on the thermal break through deformation, thus allowing thermal breaks of different thicknesses to be mounted in the mounting slot 28.

[0034] As in Fig. Figure 5 shows a pair of elastic arms 50, which, in the horizontal direction, provide support for the thermal protection (not shown). Each elastic arm 50 is designed to include an elongated flat plate 52 and a support section 54. The support section 54 projects from an end section of the plate 52 toward the interior 38. The support section 54 has a surface 56 for supporting the thermal protection so that it can come into contact with a side surface of the mounted thermal protection. The support section 54 is a movable end of the elastic arm 50.

[0035] Returning to Fig. In the figure 4, the plate 52 has a height h in the vertical direction of the wall 36, and the plate 52 occupies a certain height within the mounting slot 28, the height h being designed to be more than 1 / 4 of the height H of the wall 36. Furthermore, the wall 36 extends in the mounting direction f of the thermal protection in an extension section 42. As shown in the figure, the extension section 42 is located at the bottom of the wall 36. The extension section 42 has a cavity 44 that is connected to the interior 38. In the embodiment shown in the drawing, the extension section 42 at the bottom of the wall 36 forms a stepped structure inside the mounting slot 28, such that the interior 38 becomes a receiving location for the first phase, and the cavity 44 becomes a receiving space for the second phase.Some thermal protectors can be fully assembled by inserting them into the interior 38, while others enter the cavity 44 after passing through the interior 38. A portion of the housing of these thermal protectors remains in the cavity 44 to facilitate assembly. It is understood that creating the extension section is straightforward; only minor modifications to the existing injection molds are required.

[0036] Corresponding to the stepped structure, wall 36 has a first base support 46 for the interior space 38, and extension section 42 has a second base support 48 for the cavity 44. The second base support 48 is located deeper than the first base support 46. In the direction of the installation direction f of the thermal insulation, the first base support 46 is the step of the first phase, and the second base support 48 is the step of the second phase. The first base support 46 and the second base support 48 both act as support and boundary for the thermal insulation.

[0037] As explained above, there are many different types of thermal protection devices, including, but not limited to, conventional PTC thermal protection devices and bimetallic thermal protection devices. The core components inside these types of thermal protection devices are encased in a plastic housing, resulting in relatively large dimensions, particularly in the thickness of the housing. In contrast, there is a new type of thermal protection device with a less complex exterior; these do not have plastic housings and have smaller external dimensions and a comparatively thinner profile. These latter thermal protection devices are not suitable for installation in a mounting space designed for the previously described thermal protection devices because the mounting space is too large.In the present application, the elastic arm provides additional support for the thermal protection, and the arrangement of multiple mounting spaces for these differently sized thermal protection devices is also suitable. The present application offers the possibility of mounting different thermal protection devices in the same mounting space.

[0038] In one embodiment, the extension section 42 is designed to have a cavity 44 that is smaller than the interior space 38. The cavity 44 can accommodate a first thermal shield with a relatively small thickness, i.e., a thin or novel thermal shield. Furthermore, the interior space 38 can accommodate a second thermal shield with a relatively large thickness, i.e., a thick or conventional thermal shield. In another embodiment, the dimensions of the cavity 44 are designed to interact with the thickness of the first thermal shield. That is, when the first thermal shield is inserted into the mounting slot 28, the cavity 44 can enclose the lower part of the first thermal shield and thus limit its movement.

[0039] The Fig. 6 and Fig. Figures 7 show the assembly status of the first thermal protection device 32 and the second thermal protection device 34, respectively. As in Fig. Figure 6 shows a small part of the first thermal protection 32 positioned in the cavity 44, another part is located in the opposite, comparatively large interior space 38, the second base support 48 supports the first thermal protection 32, a prestress causes a very small deformation on the elastic arm 50, so that it supports the first thermal protection 32 in the horizontal direction. As shown in Fig. Figure 7 shows the second thermal guard 34 positioned in the interior, the first base support 46 supports the second thermal guard 34, a comparatively large deformation is caused on the elastic arm 50 by a prestress, a side surface of the second thermal guard 34 and a flange on the opposite side surface are bounded between the elastic arm 50 and a side wall opposite the elastic arm 50 (not shown).

[0040] If the pins of the thermal protector connect to the conductor tracks, the thermal protector can no longer easily leave the mounting slot. In the case of the Fig. 6 and Fig. In the embodiment shown in Figure 7, the thermal protection is limited upwards by the elastic arm on the side, and is limited by the lower part of the mounting slot, i.e. the second base support 48 and the first base support 46, and the position of the connecting pins (not shown) of the thermal protection at the opening is limited at the head end.

[0041] Returning to Fig. 5 and the Fig. 2 and Fig. 3 The elastic arm 50 is located on a side section in the mounting slot 28. In the embodiment shown in the drawing, the elastic arm 50 extends directly out of the first side 20 and forms the mounting slot 28 with the walls of the other side sections. As shown in Fig. As shown in Figure 4, the mounting slot 28 is integrated into the carrier plate 18, with the opening 40 of the wall 36 being located on the first side 20, and the first base support 46 and the second base support 48 being located on the second side 22. The mounting slot 28 is located on both sides of the carrier plate 18, so that, compared to a distribution on only one side of the carrier plate 18, the height to which the mounting slot 28 protrudes from the carrier plate 18 can be reduced.

[0042] Furthermore, a heat conduction bore 58 is arranged on the side wall opposite the elastic arm 50, see Fig. 5, and on the second base support 48 there is also a further heat conduction bore 60 arranged, see Fig. 6. In the embodiment of the drawing, the mounting slot 28 is arranged on a side edge of the carrier plate 18, so that it is located near the metal housing of the brush carrier 14, in particular the heat conduction bore 58 of the two heat conduction bores located on the side wall can transfer the heat quantity of the thermal protection to the metal housing.

[0043] According to the concept of the present application, compatibility with different thermal protection systems can be achieved by arranging several stages in the extension section to create different cavities.

[0044] As in Fig. As shown in Figure 8, the first partition 62 is shaped such that it protrudes from the second side 22 of the carrier plate and is connected to the outer surface of the mounting slot 28. The first partition 62 can be arranged in pairs. In this case, a first partition 62 is located between the circuit board (not shown) and the bearing bore 26 of the brush holder and serves to prevent carbon dust from falling from the carbon brushes onto the circuit board. In the embodiment shown in the drawing, the first partition 62 is a vertical wall 66 and is integrated into the outer surface of the mounting slot 28, separating the circuit board from the bearing bore 26.

[0045] As in Fig. As shown in Figure 9, the second partition 68 is shaped to project from the first side 20 and covers the process bore (not shown, as it is obscured by the second partition) that runs through the first and second sides of the carrier plate. In the embodiment shown in the drawing, the second partition 68 is a projection 70 and has a conical shape, which is advantageous for mold extraction. Coal dust can fall through the process bore from the first side 20 shown in the drawings to the second side, where the printed circuit board is located, i.e., to the back of the printed circuit board, which cannot be shown in the drawings. By arranging the second partition 68, it is essentially possible to prevent the coal dust from taking this path.

[0046] When the first partition 62 and the second partition 68 are integrated into the brush holder, these partitions can be formed by modifying the molds for the brush holder. The arrangement of the first partition 62 and the second partition 68 protects the printed circuit board and the electronic components on the board from carbon dust deposits, thus ensuring the proper functioning of the conductor tracks and extending the service life of all components.

[0047] Furthermore, other partitions can be integrated into the brush holder, for example by arranging partitions around the circumference of important sensors. The position and shape of such partitions depend on the objects to be protected.

[0048] The printed circuit board is located on the second side 22 of the carrier plate. Several pins 64, 65 are arranged on the second side 22, which serve to position the printed circuit board. One of these positioning pins, 65, is designed to have a different structure than pin 64. Fig. 8 and Fig. In summary, the pin 65 has a guide section 72 for traversing the printed circuit board, a positioning platform 74 as a stop to terminate the traversal of the printed circuit board, and an additional interaction section 76 between the guide section 72 and the positioning platform 74. The interaction section 76 is arranged such that it interacts closely with the bore of the printed circuit board and thus prevents the printed circuit board from falling off, particularly when the printed circuit board is turned over. In the embodiment shown in the drawing, the interaction section 76 is designed as several parts that project from the cylindrical body of the pin as an extension, the dimensions of the cylindrical body of the pin being essentially identical to those of the guide section 72. Fig. Figure 11 is a schematic representation of the cross-section of a pin according to one embodiment. As shown in the figure, the inner area marked by the circular dashed line is the cylindrical body or guide section 72 of the pin. The areas between the circular dashed line and the solid lines mark the projecting areas 78. These areas 78 fill the sections of the cylindrical body between the positioning hole 80 and the pin with the same dimensions as the guide section 72. These projecting areas 78 have arcuate outer surfaces that follow the contour of the positioning hole 80. In the embodiment shown in the drawing, the projecting areas 78 are four ribs with large, rounded corners. Several projecting areas 78 together form a square body and interact with the circular positioning hole 80 of the circuit board.

[0049] As in Fig. As shown in Figure 12, the printed circuit board 24 has a heteromorphic contour. In the embodiment shown in the drawing, the printed circuit board has a "D" shape, with the right-angled side located inside the brush holder 14 and the curved side extending along the edge of the brush holder 14. A portion is therefore cut off from the circumference of the bearing bore 26, resulting in an opening 82 that interacts with the right-angled side. As can be seen, the printed circuit board 24 does not occupy the entire area of ​​the brush holder 14, but only about half. The electronic components required for the brush holder 14 are concentrated on the printed circuit board and include, among other things, several types of capacitors, varistors, resistors, Hall sensors, and probes, etc. Therefore, the printed circuit board 24 has a high integration density, and the representation of the brush holder 14 is simplified.

[0050] At its radial outer edge, the brush carrier 14 integrates a connector socket 84, which serves to be connected to external connectors. Terminals 86, 87 are arranged on the connector socket 84, with the terminals 86, 87 being connected between the connector socket 84 and the circuit board 24. These terminals are provided with pins that are soldered to the circuit board; the terminals can be used as power or electronic components such as Hall sensors. In one embodiment, the power terminal pins are arranged so that they have the same shape, and the Hall (sensor) terminal pins are arranged so that they have the same shape. Fig. 13 and Fig. Figures 14 and 16 are schematic representations of an embodiment of a power terminal 86 and a Hall effect terminal 87, respectively, wherein the pins 88 and 89, which have the same shape, are soldered to the circuit board. The terminals 86 and 87 are arranged so that they are inserted under pressure into a slot of the connector 84. In the embodiment shown in the drawing, a protruding hook section 90 is arranged on each terminal 86 and 87. Accordingly, as in Fig. Figure 15 shows a step 94 arranged in the slot 92 of the terminal socket 84, which provides an inclined surface 96 for guiding the hook section 90. As soon as the hook section 90 passes the step 94, it rests against the step 94, thus enabling the mounting and positioning of the terminal 86 (87) in the slot 92. In the present application, the mounting process of the terminals is modified. Conventional terminals are mounted on the terminal socket by injection molding; however, in the present application, the injection molding process can be omitted, as the structural arrangement allows the terminals to be mounted on the terminal socket after molding. Fig. Figure 16 is a schematic representation of a brush carrier 14 with clamps 86, 87 already mounted.

[0051] Although the principle of the present application is explained and described in detail herein with concrete examples of its implementation, it is understood that the present application may be implemented in other ways without deviating from the described principle.

Claims

[1] Electric motor, characterized by that it includes the following: a brush carrier (14) arranged between the magnetic pole housing (12) and the drive piece, a rotor passing through the brush carrier (14) to connect with the drive piece, a mounting slot (28) arranged on the brush carrier (14), the mounting slot (28) having a wall (36) that delimits an interior space (38), and the mounting slot (28) having an opening (40) at its head end, wherein a thermal guard is mounted through the opening (40) in the interior space (38), and an elastic arm (50) is arranged on the wall (36), and the elastic arm (50) is elastically deformed to bear against a side surface of the thermal guard. [2] Electric motor according to claim 1, characterized by, that: the elastic arm (50) comprises an elongated plate (52), the plate (52) has a height (h) in the vertical direction of the wall (36), the height (h) of the plate (52) is more than 1 / 4 of the height (H) of the wall (36); and the brush holder (14) is formed from plastic by injection molding. [3] Electric motor according to claim 1, characterized by , that: the mounting slot (28) is designed such that the position of the thermal guard in the mounting slot (28) is limited by means of the lower part of the mounting slot (28), elastic arm (50) and the connecting pins of the thermal guard at the location of the opening (40). [4] Electric motor according to claim 1, characterized by, that: an extension section (42) extends on the wall (36) at the lower part of the mounting slot (28), the wall (36) has a first base support (46), the extension section (42) has a cavity (44) that is smaller than the interior (38), and a second base support (48) that is deeper than the first base support (46), wherein the second base support (48) is designed to support the first thermal shield (32), and the first base support (46) is designed to support a second thermal shield (34) that is of a different size than the first thermal shield (32). [5] Electric motor according to claim 2, characterized by, that: the elastic arm (50) is located on a side wall in the mounting slot (28), the elastic arm (50) comprises a support section (54) that projects from an end section of the plate (52) towards the interior (38), the support section (54) has a surface (56) that abuts a side surface of the thermal protection; wherein a heat conduction bore (58) is arranged on the side wall opposite this side wall. [6] Electric motor according to claim 1, characterized by, that: the mounting slot (28) is integrated into the brush carrier (14), the brush carrier (14) comprises a support plate (18), the support plate (18) having a first side (20) and a second side (22) opposite the first side (20) on which carbon brushes are arranged, a printed circuit board (24) being arranged on the second side (22); the elastic arm (50) being shaped to project from the first side (20); the second partition (62) being shaped to project from the second side (22) and being connected to the outside of the mounting slot (28), the first partition (62) being located between the printed circuit board (24) and the bearing bore (26) of the brush carrier (14), the rotor being supported by the cooperation of the bearing bore (26). [7] Electric motor according to claim 6, characterized by, that: the second partition (68) is shaped such that it protrudes from the first side (20) to cover the process bore which passes through the first side (20) and the second side (22) of the carrier plate (18). [8] Electric motor according to claim 6, characterized by, that: on the second side (22) several pins (64, 65) are arranged to position the printed circuit board (24), any one of the pins being configured to have a guide section (72) passing through the printed circuit board (24), a positioning platform (74) as a stop to terminate the passage through the printed circuit board (24), and an interaction section (76) between the guide section (72) and the positioning platform (74), the interaction section (76) interacting with the positioning hole (80) of the printed circuit board (24); and the interaction section (76) being configured as several parts (78) extending the cylindrical body of the pin (65) to provide a fill between the positioning hole (80) and the pin (65), each of these parts (78) having an arcuate outer surface that follows the corresponding contour of the positioning hole (80). [9] Electric motor according to claim 6, characterized by, that: the printed circuit board (24) is designed to have a heteromorphic contour; wherein the circumference of the bearing bore (26) has a passage (82) in which a part has been cut off to interact with the contour of a part of the printed circuit board (24), wherein the contour of other parts of the printed circuit board (24) follows the shape of the brush carrier (14). [10] Electric motor according to claim 1, characterized by , that: the brush carrier (14) integrates a terminal socket (84) on its radial outer edge, and that several terminals (86, 87) with pins (88, 89) are inserted under pressure into a slot (92) of the terminal socket (84) to establish a connection between the terminal socket (84) and the circuit board (24) mounted on the brush carrier (14).

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